code: def update(self):
      # keep looping infinitely until the thread is stopped
      for f in self.stream:
          # grab the frame from the stream and clear the stream in
          # preparation for the next frame
          self.frame = f.array
          self.rawCapture.truncate(0)
  
          # if the thread indicator variable is set, stop the thread
          # and resource camera resources
          if self.stopped:
              self.stream.close()
              self.rawCapture.close()
              self.camera.close()
              return
  
file_path: imutils/imutils/video/pivideostream.py
imports: from picamera.array import PiRGBArray
  from picamera import PiCamera
  from threading import Thread
  import cv2
label_desc: Use image node_id 3 for calling the PiVideoStream obj's underlying member method code with example usage: obj.update() without return types